1. Field of the Invention
This invention relates to a liposuction apparatus and method. More particularly, this invention relates to a liposuction apparatus optionally having a sonic or ultrasonic source with an axial lumen passage in which the shaft can be made to reciprocate in a non-rectilinear fashion. The apparatus and method may also contain the concomitant use of rectilinear reciprocation motion in addition to ultrasonic motion or energy along the shaft of said device.
2. Description of the Prior Art
Liposuction, which literally means “fat suction”, is a technique to remove intact fat cells, fat globules, fatty fluids or fatty debris from the body by means of teasing, pulling, scraping, sonication, suction and/or pressing out the debris. Liposuction can be used to reduce the volume of fat in many regions of the body, but liposuction is particularly effective in such areas as the thighs and the abdomen where fat is less responsive to diet and exercise. Liposuction, performed as an elective operation, is one of the most common surgeries performed in the world.
There are now several main forms of liposuction used by surgeons to extract fat. Each of these modalities varies in its necessity or usefulness, depending upon the area of the body being treated, the amount of fibrous tissue which is mixed in with the fat to be treated, the number of times the fat has been previously suctioned (which usually increases the fibrous and resistant nature of the fat), and the genetic makeup of the individual patient (African-American and Mediterranean ancestry patients and males usually have more fibrous fat). Herein follow some of the condensed benefits and more expanded upon drawbacks of each modality so as to differentiate our proposed devices from the prior art.
In traditional liposuction, a single lumen cannula shaft, attached to a handle, is pushed by a surgeon through skin entrance sites into the target fat in a spoke-wheel or radial fashion. Unfortunately, chronic and acute stress on the surgeon's elbow and shoulder can fatigue the surgeon, thus reducing the reproducibility of the result between the patient's right and left sides, and sometimes making for a less than optimal result. When a liposuction cannula passes through the target tissue, it tends to suck out or traumatize a diameter of fat that is related to the diameter of the shaft of the cannula, Ideally, one would use the smallest diameter shaft possible to reduce penetration injuries. Unfortunately, liposuction would take excessive time to perform with ultra-small (less than 2 mm) cannulas. Some surgeons utilize small cannulas that vary on the size of syringe needles. This work takes numerous hours to perform and is impractical for the average surgeon with typical time and anesthetic constraints. Additionally, the performance of numerous liposuction procedures and the necessity to move the surgeon's arm back and forth so many times within a unit period of time has led to surgeons having physical conditions similar to tennis elbow and arthritis of the involved joints. Most surgeons thus use larger single lumen cannula shafts, up to 4 to 6 mm in diameter. Unfortunately, these larger diameter cannulas often leave noticeably large waves behind in the patient's target fat area and surface skin resulting in an unpleasant, non-uniform appearance to the skin.
In a review by Weber et al, Reinforced Swan-Neck, Flexible Shaft, Beveled Liposuction Cannulas (The American Journal of Cosmetic Surgery) 16(1): 41-47, 1999, dynamics Of liposuction cannula tips were discussed. Although smaller tips and shaft diameters require less energy from the surgeon to penetrate fibrous fat, less fat per unit time is removed. Larger diameter cannulas remove fat faster, but require greater effort and tissue trauma. It is difficult to find a happy medium, although sometimes the choice of a cannula tip can reduce the exertion necessary to pass through fibrous fat. (See above referenced Weber et al, American Journal of Cosmetic Surgery.)
Ultrasonic liposuction cannulas were developed by Parisi et al in the late 1980's and patented under the patents “Liposuction procedure With Ultrasonic Probe”, U.S. Pat. No. 4,886,791 and “Ultrasonic probe”, U.S. Pat. No. 4,861,332 (1988). Parisi claims that the ultrasonic process “melts” fat. Only if the word “melt” is used extremely loosely and re-defined is this true. Fat stored in the body may be encapsulated in cells and is not truly solid to any degree. The ultrasonic cannula uses water as a coupling medium in order to break apart fat cells and fat globules, thus releasing fat from the aforementioned cells and fibrous tissues which provide support and structure to the human fat. Parisi saw early on that the tremendous heat generated by the ultrasonic liposuction cannula could be detrimental to the patient and therefore requires significant cooling measures. The material which follows will demonstrate three generations of ultrasonic liposuction cannulas based upon the Parisi patents, which still do not provide an adequate solution.
Three (3) Generations of Ultrasonic Liposuction:
The newest (third generation) ultrasonic liposuction cannula is basically cooled along the length of the cannula shaft by an outer metal sleeve that almost covers the vibrating tip. Sterile cooling water passes between the hot inner vibrating shaft and the outer metal sleeve. The cooling water exits at the tip of the cannula as a “bubble” of water. Disadvantageously, the metal cooling sleeve leaves only a fraction of an inch of vibrating shaft (tip) exposed to the patient's tissue. This design change is alleged to reduce the tendency for thermal burns. A major drawback for the third generation of ultrasonic cannulas is that there is incomplete suction of the sonicated (broken and foamy) fat out of the patient's tissues. The broken down fat remaining in the patient must be crudely pressed out with rollers, suctioned out with old-fashioned cannulas or left to be “absorbed” inside the patient's body. The long term effects of leaving foamy fat and broken down fat cells behind in the body have not been determined. For example, degraded fat may cause more fibrosis of the treated areas, or the liver or vessels may be damaged by fatty infiltration due to overload.
The third generation still suffers the possibility of causing thermal burns wherein a hot cannula tip strikes or harms the skin. Another problem with ultrasonic liposuction is that the tip can become extremely hot when impacting a dense bodily structure if the ultrasonic cannula is moving too slowly.
Some of the disadvantages of ultrasonic liposuction, no matter what generation of cannula is used, are currently unknown to many patients. Ineffectively, surgeons use rolling pins to “squish out” the remainder of the liquefied fat out of the patients. This means that the current ultrasonic cannulas are suction-inefficient, perhaps leaving up to one-half of the sonicated fat behind. Current cannulas do not have holes large enough or exposed enough to completely suction-up the fat that is sonicated and liquefied. Fatty acids are a known source of inflammation in the human body and may cause the body to lay down scar tissue and other unwanted reactions. Additionally, the tunnels and unsonicated liquefied oils and their by-products likely contribute to the formation of seromas (fluid ball collections) so commonly seen with ultrasonic liposuction procedures. Using rollers is not an optimal way to remove fat and is only partially successful, Current ultrasonic liposuction cannulas cannot bend sufficiently and still vibrate (sonicate) the desired target structures. Early generations of ultrasonic liposuction cannulas, which are still currently in use in many offices throughout the United States, incorporate large “protectors” that are screwed into the patient's skin to protect the entrance sites from burns. These “protectors” make for even larger scars at the entrance wounds. Another disadvantage of the third generation liposuction cannula is that the cooling sleeve portion adds 2 mm to the diameter of the cannula. The current long-shaft version of the third generation ultrasonic liposuction cannula has a diameter of over 6 mm. Larger entrance sites (wounds) cause larger scars following the procedure. Ultrasonic liposuction is most helpful in areas of the body that are very thick and fibrous, e.g., areas where liposuction is being done for a second or more time, the back region, and the male breast region where the fat can be thick and heavily coursed by fibrous tissue.
Some surgeons feel that they produce safer and less burning results with the latest ultrasonic cannulas when the cannula setting is reduced to 50 percent maximum energy. Unfortunately, this 50 percent ultrasonic energy reduction results in a more difficult passage of the cannula through fibrous fat. It would, therefore, be highly desirable to be able to reduce the ultrasonic energy necessary to penetrate the fibrous or target fat by the addition or combination of another energy source within the liposuction cannula shaft.
There are three primary sources of energy that may be applied to the cannula shaft. The slowest of motions is the oscillating surgeon's arm motion, approximately one to two hertz. Intermediate 100 hertz motion is provided by reciprocating action (see below). Motion at 25,000 hertz may be delivered via ultrasonic energy.
In an effort to reduce the energy required for the surgeon's arm to bore through fibrous fat, in the late 1980's a 100 hertz rectilinear motion induced by motors was proposed for the cannula handle. Some of the early prototypes for rectilinear motion were manufactured (well prior to patents being issued) for individuals by KMI (Kolster Medical Inc.) in Los Angeles, Calif. Discussions with Mr. Kolster revealed that in the late 1980's KMI was already manufacturing reciprocating rectilinear liposuction cannulas. The frequency of oscillation of the shafts was roughly 100 hertz. In the past there were difficulties with cost and sterilization considerations, as well as durability following numerous sterilizations. Since the late 1980's there have been several patents granted for various reciprocating liposuction cannula devices.
Although the reciprocating devices which have been previously patented and/or are in clinical use do cause rubbing, abrasion, shearing or tearing of the fat globules as they fall into the reciprocating cannula tip, it is possible that the true principal dynamic involved in the use of a reciprocating device is to expose a greater amount of cannula tip port to the external fat to be suctioned. For example, if a 2 mm wide by 10 mm long cannula fat entrance port were to oscillate on an arc 2 mm to the right and 2 mm to the left, the effective surface area (size) of the port would be tripled. Additionally, if a 2 mm, wide by 10 mm long cannula entrance port were reciprocating in a to and fro direction and it reciprocated 5 mm forward and 5 mm backward, this would only double the effective zone in which fat (or aspirate) could be entrapped.
It has been shown that additional but relatively small amounts of ultrasonic energy can loosen target fat sufficiently and enhance the procedure.
The prior efforts rely upon the process of slicing or cutting in which two shafts, both an inner and an outer shaft, move in dissimilar directions, align windows for an instant (allowing a window or port of availability for the fat to fall into at the very distal tip and be sliced off), followed by alleged “cutting” as the two shafts and windows move again in different directions. Any surgeon who has performed a sufficient number of liposuctions will be able to verify that the fibrous sepral bands which course through the fat nourish it and provide support, and are of a very strong nature similar to the tough white bands found in steaks that are uncooked. It is highly improbable that any of the prior art just described would succeed in operating for sufficient time to complete a typical procedure without becoming completely clogged with fibrous tissue or having fibrous tissue catch in between the dissimilarly moving shafts, thus ceasing operation of the proposed devices. These devices in non-disposable form would likely be impractical for common usage in liposuction, especially in large areas in which the target fat is fibrous in nature. Fibrous target fat exists in one of every two patients.
Further embodiments of the prior art include motors for the reciprocation which are powered by electricity and/or gas. Close inspection of the prior art reveals that none of the gas-powered instruments utilize the available excess vacuum power that is present currently in all of offices that are performing liposuction. Since the late 1980's the vacuum-powered suction machines have become exceedingly strong, capable of delivering vacuums of −40 torr. The non-electrical prior art basically relies upon gas-powered mechanisms that provide a positive pressure in order to generate the energy by which a reciprocating mechanism can be driven. Motors or pressurized gas cannisters cost money in that the positive pressure fluid source must be used to generate the power. Additionally, mechanization must be present within the liposuction cannula to utilize the positive pressure power. Additionally, extra hoses must come into the liposuction cannula, thus causing a tangled hose mess for the surgeon who is already having to keep up with two additional hoses (if ultrasonic suction is performed with a water cooling hose and an electrical control line), which is in addition to the suction line.
The liposuction device and method of the present invention is dissimilar to the prior art apparatus in that in this invention the cannula shaft does not require two separately moving shafts in order to catch fat between two aligned “windows” or to cut and remove fat. Also, the present invention differs from the prior art in that only a single shaft is necessary to effect the removal of the target fat. A second shaft or additional lumen is also in the present invention but its design, function and purpose is for the novel combination of cooling the tip of the hot vibration ultrasonic device, and optionally to equilibrate the pressure or provide additional pressure in order to allow fat to move back up the cannula shaft with greater ease as opposed to traditional and previous ultrasonic liposuction cannula shafts. The liposuction device of this invention involves a novel combination of the uses of reciprocating energy (e.g. at 100 Hz) plus ultrasonic energy (e.g. at 25 KHz) in which the dual use of both energies would reduce the total energy of each specific type, i.e., reduced ultrasonic energy and reduced reciprocating energy to be used, In addition, the device of this invention may uniquely use suction (vacuum/negative pressure) to cause a desired and controllable reciprocating motion of the liposuction shaft. For example, vacuum pump capability approaches −40 torr, but optimally only mild negative pressure in the range of −10 to −15 torr is used for suctioning in order to reduce trauma to the fatty tissues. Excess vacuum capacity may be utilized to generate reciprocating motion within the cannula shaft.